Welcome to the forums tarikduh!
So basically I'll just echo/confirm Glasses. You can
definitely transfer internally to that double degree; a heap of people transfer into Law degrees internally. You are
never completely locked out of studying what you're passionate about. So don't be too discouraged that things didn't quite go your way last year - If you stay driven and work hard you will still get where you want to be!
Unfortunately writing a letter isn't going to achieve much - These universities deal with so many applicants it just isn't going to have an effect. Here's what I think you should do:
- Enrol in that Bachelor of Community and Criminal Justice, assuming it is something that interests you!
- Keep the double degree at the top of your preference list and keep an eye on subsequent offers - I don't know your results, but you might get an offer to it in a later round! Then if you do you just cancel your enrolment in the first degree and pick up the double.
Keep your chin up - Hard work gets places, even if it isn't the way you expect